James maokaye



UNITED STATES PATENT OFFICE.

JAMES MAOKAYE, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR TO RIVER SMELTING 86 REFINING COMPANY, OF ST. LOUIS, MISSOURI, A CORPORATION OF MAINE.

BASIC EERRIC SULFATE AND METHOD OF PREPARING SAME.

No Drawing.

To all whom it may concern:

Be it known that I, JAMES MA KAYE, a citizen of the United States, residing at Cambridge, in the county of Middlesex and State of Massachusetts, have invented an Improvement in Basic Ferric Sulfate and Methods of Preparing Same, of which the following is a specification.

My invention relates to the production of a basic ferric sulfate, soluble in dilute sulfuric acid, from ferrous sulfate or commercial copperas and to the product so made.

In the preparation of a ferric salt, either for use as purifier for salt solutions such as zinc sulfate solutions used in the production of electrolytic zinc, or for other purposes, it has been customary to start with the cheapest salt of iron, generally copperas, or ferrous sulfate. It is necessary to oxidize these salts, either dry or in solution, to the corresponding ferric form and this oxidation has been attended with considerable difficulty and expense.

I have found, however, that copper-as, or crystallized ferrous sulfate, in a more or less powdered or granular form, under certain conditions, may be converted into a ferric salt which is soluble in sulfuric acid, by air alone and without other treatment and in a comparatively short time.

It is well known that copperas, when exposed to the action of the air at normal temperature is superficially converted very slowly into a basic ferric sulfate, but a conversion of copperas by this means to a ferric soluble in sulfuric acid is not practicable.

It is also well known that ferrous sulfate,

when heated to a high degree, is converted to a ferric form, ferric oxid. In this form it is insoluble in dilute sulfuric acid, or pragtically so, and consequently cannot be use I have found, however, that when copperas, or ferrous sulfate, in a more or less powdered or granular form is subjected to a moderate degree of heat in contact with air, the ferrous salt is rapidly converted into a basic ferric sulfate soluble in dilute sulfuric acid without othertreatment, and whereas, by the heating of the ferrous salt to a high degree, it is converted to an insoluble ferric form, the moderate heating of the ferrous salt in finely divided form in contact with air converts it into a soluble Specification of Letters Patent.

Application filed September 13, 1918.

Patented Sept. 23, 1919.

Serial No. 254,022.

ferric form which, upon standing a few hours in contact with dilute sulfuric acid, goes into solution.

I find that at a temperature of from 200 to 300 centigrade in contact with air the ferrous sulfate is readily converted to the basic ferric sulfate invented by me which is soluble in dilute sulfuric acid although the temperature at which the salt is treated in the presence of air may vary considerably without appreciably affecting the results of the process. Temperatures much lower than those cited result in an incomplete or impractically slow oxidation, while temperatures greatly exceeding those cited render the product insoluble in dilute sulfuric acid and so unavailable for use in electrolytic zinc processes. However, as before stated, the temperature to which the ferrous sulfate may be heated may depart considerably from the values cited Without appreciably affecting the results of the process.

Any type of apparatus may be employed in which the copperas is heated in the presence of air. Preferably it should be such that the heated granules or particles of copperas are continually agitated during their treatment to thereby facilitate their conversion.

A type of apparatus well suited for the purpose is the common rotary drier which consists merely in a rotatable iron cylinder heated to the required temperature by any suitable means. The cylinder is preferably provided, on the inside, with radial fins which, as the cylinder rotates, continually lift and drop the particles and thereby expose them constantly to the action of the air.

The material may be fed continuously through the drier by rotating the cylinder on an axis slightly inclined to the horizontal, or the cylinder may be rotated on a horizontal axis and the copperas oxidized in batches.

In the above described treatment of the copperas, the resultant product assumes the form of very fine dust which may escape in considerable quantities from the open ends of the oxidizing cylinder. To prevent this objectionable escape of product the ends of the cylinder may be closed to prevent the exit of the dust but not closed for the entrance of air to the copperas under treatment. If desired, one end of the oxidizing cylinder may be connected with a gas filter of any suitable construction and the other end left open and the air necessaryforthe oxidizing'of the" material "maybe d'ravi n throughthe filter from the open end or the cylinder by means of a fan. 7

Whereas I ha edescribed a simple type of appana tus'well adapted for the conversion, by heat, of copperas or ferrous sulfate, to a soluble ferric form, basic ferric sulfate, yet

other types of apparatus may also be equally efficacious operation. In fact, the mater al uld h ade b h ati n a d h a d stirring the heated product ith a spoon.

is w ll known that in practice there is no "chel iical formula for basic ferr-i al elie e l' h -Prod Of m P o i 9 exc ptieh to th ru b my compound i ead l d tin ish om other b i i ill hl at s by t efaa t e? it is eadi y sel h e i i dil te .s ss es d lt h e n t isfreasofnably stable sofa!" as this quality is concerned. 7

The r iz h on in hp re ent rs e th reect qh t e xt t es eii'Y- to eqih le s the p edu a f u e, if an aah dr aS ferrous sulfate were used, the wea y em nt h i be te emele h bas r i S t a by e additi n qf' lno ur i e f -m e conversion of the copperasneed not be whi lash harrie Q t- A c e s on of over-98% is obtained by my method and P eht e t in he ed h h lh s plli l l d- 7 l a i 10min! 1'.

T -method of oxidizing ferrous sulfate ferricsulfate soluble in dilute i lfillf d acid which hsist m erat y eeisae this Ret s a he eb'i i ed or heating ferrous sulfate in granular form in contact'with air.

2-; The method of oxidizing ferrous sulfate inundissolved form to basic ferric sulfate which consists in heating said ferrous sulfate at'an elevated temperature below that at which it is converted into ferric form insoluble in dilute sulfuric acid in intimate contact With air.

3. The method of oxidizing ferrous sulfate in undissolved form to basic ferric sulfate Which consists in heating, said ferrous sulfate at a temperature below that atwhich it is converted into ferric form insoluble in dilute sulfuric acid in, intimate Contact w th a 4. The method of preparing a basic ferric sulfate Which consists in subjecting copperas in "granular form to atemperature from about 200 degrees to about 0degrees ce tigrade in intimate contact with an eX- esw e 5 method of preparing a basic ferric sulfate which consists insubjecting ferrous sulfate in granular form to a temperature from about 200degrees to about 300 degrees centigrade in intimate contact With an excess of air by agitation. r

A basicferric sulfate characterized by being soluble in dilute sulfuric acid as described."

In testimony whereof; I have signed my name to this specification, in the presence of two subscribing. Witnesses.

Witness' I H DA .T..T. GREENWOOD.

Washing o n. c.

. JAMES, MAGK YE.

five cents each, by addressing the tlommissioner of Patents. 1 Y 

